1. Field of the Invention
The present invention relates to an ink-jet head, an ink-jet printer using the same, and a method of manufacturing the ink-jet head.
2. Description of the Related Art
Conventionally, there is known an ink-jet head in which a piezoelectric element is driven, ink filled in a pressure chamber adjacent to the piezoelectric element is pressed, and the ink is jetted to a recording medium such as a paper from a nozzle communicating with the pressure chamber, so that an image is formed on the recording medium. In this kind of ink-jet head, in order to obtain an excellent picture quality, it is necessary to uniformly discharge the ink from each nozzle, and in order to raise the discharge performance of ink, various techniques have been conventionally developed.
For example, in a drop-on-demand type ink-jet head as disclosed in JP-A-1-178451, in order to prevent jets of ink droplets from becoming unstable due to a decrease in damping effect of an ink reservoir and to prevent mutual interference between nozzles, dummy nozzles are provided in the ink-jet head in addition to original nozzles, and a pressure wave generated in an ink pressure chamber at the time of jetting and transmitted to the common ink reservoir is absorbed by using the dummy nozzles.
Besides, in recent years, there is known an ink-jet head in which plural lines of pressure chambers are formed in a cavity plate, and a piezoelectric sheet in which a drive electrode (so-called individual electrode) is formed for each of the pressure chambers of the cavity plate is joined to the cavity plate.
In this type of ink-jet head, voltage is applied to the respective drive electrodes of the piezoelectric sheet, and the ink in the pressure chambers corresponding thereto is jetted from nozzles. Thus, when the respective areas of the piezoelectric sheet driven by voltage application to the respective drive electrodes do not have uniform characteristics, it becomes difficult to uniformly jet ink droplets from the respective nozzles and to obtain an excellent picture quality.
In recent years, in order to raise the resolution of an image, it is required to narrow the arrangement intervals of respective pressure chambers and drive electrodes. However, the characteristic of each area of the piezoelectric sheet is greatly influenced by its surrounding structure. Accordingly, when the arrangement intervals of the respective pressure chambers and drive electrodes are narrowed, it becomes difficult to uniform the characteristics of the respective areas because of the influence.